May is the month when the warmer, sunnier days arrive. Are you worried that you may have missed the boat for planting your favourite varieties? Well, fear not as there are still lots of seeds to sow in May. The higher temperatures make the soil perfect for sowing seeds as warmth is vital for germination.
Sowing seeds in May
It’s important to remember that growing conditions in May can vary dramatically across the country, and can differ from county to county and even locality so keep an eye on the weather, temperature and soil conditions before you begin sowing. Some vegetables such as sweetcorn, courgettes, marrows, tomatoes and runner beans are temperature sensitive crops. If these seeds are sown in soil that is too cold germination will be poor and any seedlings that do appear won’t crop as well as those started out in warmer soils. For these seeds keep them indoors in a greenhouse or propagator to give them the best chance.
By late May, it’s highly likely that the risk of frost has passed which means that many seeds can be sown directly into the soil outside. Saying this, it’s still best practice to check the seed packet instructions to make sure you’re meeting the seeds’ optimum growing requirements (e.g. depth of seed, temperature etc.).
Here’s our list of seeds to sow in May.
Flower seeds to sow in May
- Cornflower – sow directly outside to help attract wildlife to your garden.
- Nasturtiums – sow outside in pots containers and in borders. Seeds usually take up to two weeks to sprout, although if prepared properly before planting outdoors, the seeds can often germinate within seven days.
- Poppy – directly sow seeds outside for germination within 7-30 days. You’ll have to wait until the following summer for a healthy display of poppies. This will help you to attract butterflies and bees to your garden.
- Sunflower – directly sow outdoors now for flowering this year in late summer and autumn. Read our article for advice on how to grow sunflowers.
Sow indoors in a greenhouse:
- Aquilegia, Delphiniums and Lupins – sow these perennial seeds indoors in a greenhouse for flowering next year and for many more years to come.
- Foxglove and Sweet Williams – sow these biennial flowers in trays in the greenhouse ready for flowering next year.
Vegetable seeds to sow in May
- Beetroot – Directly sow seeds thinly into the ground. Do this by sprinkling the seeds sparingly so that there is space between each seed.
- Broccoli – sow directly into your vegetable plot or if the weather is too cold, sow in a nursery bed for transplanting outside when the weather gets warmer.
- Brussel Sprouts – sow directly in your vegetable patch outdoors.
- Carrot – sow in rows and protect the crop with fleece to prevent a possible carrot-fly attack.
- Chives, Coriander, Dill and Parsley – sow directly into containers outside.
- Peas – sow directly into the ground in flat-bottom, in a zig-zag pattern drills (rows)
- Radish – sow directly into the ground.
- Spring Onion – sow seeds in drills (rows) outdoors. These are quick growing crops and are perfect for adding to salads.
- Swede – sow seeds in a rich, fertile soil outside so they are ready for harvest in autumn and winter.
Sow indoors in a greenhouse:
- Courgette, Cucumber, Squash and Pumpkins – sow seeds under cover
- French Beans and Runner Beans – sow seeds in module trays and plant out when the chance of frost has passed
- Lettuce – sow directly into the ground or in containers
- Rosemary, Sage and Thyme – sow these perennial herbs inside under cover
- Sweetcorn – start off in module trays so they are ready for planting out once the risk of frost has passed. It’s a good idea to sow at least 12 seeds.
- Watercress – sow in containers and make sure they sit in 2-3 inches of water at all times
Seed sowing equipment
- You will need either seed trays, module trays or pots with drainage holes.
- We recommend using John Innes Seed Sowing Compost or Gro-Sure Seed and Cutting compost to give your seeds the right start.
- Choose the seeds you’d like to grow. For a wide selection of flower and vegetable seeds visit our Unwins website.
- Hand trowel
- Cling film, glass or a heated propagator with lid
- Use Gro-Sure Seed Start to improve chances of seed germination
How to sow seeds
Need some help? Our step-by-step guide to sowing seeds has all the information you need.
Read our article for advice and inspiration on what other jobs you can do outside in the garden in May.